In-coupling light to a waveguide of an optical device can present various challenges. Depending on the image to be guided, the size of the waveguide, and/or grating structures to be used in the waveguide, different challenges may exist. Conventional input couplers may cause a waveguide to provide suboptimal image projection and retard optical clarity at the yielded field of view (FOV) of a resulting image output of the optical device. Such results may be particularly acute in optical devices used in head mounted display (HMD) devices. Accordingly, improved input coupling is desired to overcome challenges discovered when in-coupling image light to a waveguide of an optical device.